Guide to my rating method (notes on my odd application on 10s):
The most important detail will likely make the rest of this explanation easier. I award 10 (Masterpiece) with emphasis on the "Masterpiece" aspect, generally disregarding the objective considerations of the 10-point scale.
I often associate Masterpiece with the concept of a "classic" or major "influential" work. Thus, I have a very clear criteria for awarding my 10s.
-Generaly, the anime must be at least ten years old
-I award only a maximum of two 10s per year
-The work must be highly/originally influential, a literal "masterpiece", and/or surpass the literary or artistic qualities of anime of the time
-I rate anime differently at first, and it doesn't impact the awarding of the 10 later on. An anime with an objective rating of 5 might get a 10 later from me.
Essentially, I grade all my anime on a 9-point scale, with 9 being perfect short of the "Masterpiece" qualities listed above.
As a general rule, I believe all anime have a purpose and each have their own purposeful qualities. Given that, I only award 1s to anime which, objectively, serve no purpose whatsoever (on informative, entertainment, or other values). Generally, recap/summary episode/ovas are the only ones to receive the ground-raking number.